1. Field of the Invention
Example embodiments of the present general inventive concept relate to semiconductor devices and methods of forming the same, and, more particularly, to semiconductor devices including redistribution line structure and methods of forming the same.
2. Description of the Related Art
A chip scale package (CSP) is a type of integrated circuit chip carrier. The pads may be etched or printed directly onto the silicon wafer, resulting in a package very close to the size of the silicon die. Such a package is typically called a wafer level chip scale package (WL-CSP) or a wafer level package (WLP). The WL-CSP uses redistribution or rerouting of a bonding pad of a semiconductor chip.
In a semiconductor device fabrication process, the WL-CSP directly redistributes another pad larger in size in place of the bonding pad on the semiconductor chip. An external connection terminal, such as a solder ball or a bonding wire, is formed on the redistribution pad.
The conventional structure of a redistribution layer (RDL) typically includes several layers, such as a first interlayer dielectric, a seed metal deposition, a photoresist pattern, electroplating, a photoresist strip and seed metal etch, and a second interlayer dielectric. The WL-CSPs are typically small in size and light weight. However, the cost of raw materials and the processing costs required in their production are expensive. That is, WL-CSPs are typically more expensive to manufacture than conventional plastic packaging. Forming multiple redistribution layers and forming patterns using a photomask can have high manufacturing costs, which poses problems in mass production of WL-CSPs.
Recently, nano-scale metal particles have been developed, and include materials such as copper, silver, gold, and the like. These nano-scale metal particles can be directly drawn onto a semiconductor wafer by an ink-jet system. By using these nano-scale particles, a desired redistribution layer pattern can be drawn on the wafer by an ink-jet printing method. The redistribution line using the ink-jet method can form a metal line without a photo mask, but has difficulty in forming a very fine metal line on the wafer because the liquid line can be electrically interrupted by the surface condition of an insulation layer that is below the distribution line. It typically takes an increased amount of time to form liquid lines, because the ink-jet dotting on a wafer to form lines is usually repeated several times (such as 4-6 times) in order to form a line of a desired width.